Characterization of calotropis procera root peroxidase and its potential to mediate remediation of phenolic pollutant from petroleum refinery effluent

Abstract

Peroxidases are oxidoreductive enzymes that have the potential to oxidize recalcitrant organic compounds like phenol, reducing their toxicity. Calotropis procera root peroxidase (CPrP) was isolated, characterized, and evaluated at the laboratory scale for its ability to oxidatively degrade phenol in petroleum refinery effluent. Ammonium sulfate precipitation, ion exchange, and gel filtration chromatography were used to purify CPrP 79-fold. Purified CPrP revealed a single polypeptide band with a molecular weight of 46.5 kDa in a single peak. The biochemical characterization revealed that the CPrP is a thermostable enzyme, active on both tested substrates (o-dianisidine and guaiacol) with optimum activity at 50°C and pH 6.0. The kinetic data show that o-dianisidine is the most preferred substrate. Apart from acetone, ethylenediaminetetraacetic acid, and Hg2+ which act as inhibitors of CPrP, all other tested metal ions (Mg2+, Zn2+, Cu2+, and Mn2+) exhibited slight activation. The CPrP exhibits high efficiency to bioremediate phenol from petroleum effluent. In conclusion, this study revealed the possibility of obtaining peroxidase from locally available bioresources with the ability to bioremediate phenolic contaminants from petrochemical industry effluents.